


We've always been what we will always be

by psychomachia



Category: Fate/Zero, Fate/stay night & Related Fandoms, Sensha Otoko: A True Tank Story
Genre: Alternate Timelines, Alternate Universe - Canon AU, Crossing Timelines, Gen
Language: English
Status: Completed
Published: 2018-12-17
Updated: 2018-12-17
Packaged: 2019-09-20 03:14:54
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,411
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17014566
Author URL: https://archiveofourown.org/users/psychomachia/pseuds/psychomachia
Summary: Diarmuid is determined to be the best big brother that his little sister ever had. Waver just goes along with it.





	We've always been what we will always be

**Author's Note:**

  * For [Heart_of_Targness](https://archiveofourown.org/users/Heart_of_Targness/gifts).



> For those unfamiliar with the more whimsical Fate spinoffs, Sensha Otoko started out as an April Fools' Day 2009 joke by TYPE-MOON, as a parody of Densha Otoko, with Iskander as the otaku and genderswapped Waver as the young woman. Things sort of spiraled from there. This is based on the manga, which you can find at: https://archive.org/details/manga_Sensha_Otoko_A_True_Tank_Story. In the grand tradition of the Fateverse, timelines may have been fudged a little.

### Zero (5)

“When you were born,” Mama says, “I knew at once that you were the most special, the most beautiful baby in the world.”

Diarmuid blinks up at her. He is five years old, so he isn't really sure what she is talking about, but she's smiling at him, so he laughs. “Mama.”

“So special,” she repeats. “Which is why I want to let you know that even though there is going to be another baby in the house, you will always be my most precious baby boy.”

“Baby?” he asks.

Papa clears his throat. “What your mother is trying to say is that you're going to be a big brother and things are going to change.”

“But not that much,” Mama says. “You're always going to be my number one!”

Papa looks unhappy and Diarmuid squirms. He doesn't want to see them fight again. So he wiggles his way out of her arms and goes to find his stuffed animal. Papa says he's getting too old for it, but Mama always brings it back to him any time Papa tries to hide it.

He hugs Mr. Lion very tightly. “Baby,” he repeats. Maybe they can give it back. 

And days pass and there's no baby and Diarmuid starts to think, well, maybe Mama was just trying to make him laugh because Papa is always so grumpy and busy with work and only has time for Mama.

But then one morning, he's woken up by Papa and told that they're going to the hospital because Mama had her baby. Diarmuid wants to take Mr. Lion, but Papa makes him leave it.

So they go into a place with a lot of white walls and bright lights and get in an elevator. Everyone's smiling at them once they get out and they point down the hallway. They walk for a little bit until they get to a room and Papa opens the door to go inside.

Mama's lying on a bed, and she looks tired, but once she sees him, she gets really happy. “There's my precious baby boy,” she says. She's holding a little pink blanket against her chest. “Don't be scared.”

He goes over to her and peeks at the blanket. “Baby!” he says, and she laughs. “It's your sister.”

The baby's eyes are squinted shut, but they open a little. She makes a little noise. “Did you want to hold her?” Mama asks. He nods and she moves her carefully so the baby is tucked into his arms. “Be careful.”

“I will be!”

“Now that you're a big brother,” Papa says, “you have to look out for her. You're not the baby anymore.”

“Kayneth, honestly,” Mama says and they might start fighting, but Diarmuid doesn't care.

“I'll look out for you,” he whispers. “I'll always protect you.”

 

### Three (8)

Her name is Waver (which Papa always wrinkles his nose at, like he smells something bad, but Mama says that it's a family name and he's just going to have to get over it). She's tiny and her hair isn't curly like Diarmuid's but straight, though it's just as dark.

Neither one of them look like their parents, but they look like each other, so Diarmuid is happy. It means they're the same, right? Even if Mama doesn't love her like she loves him. 

He knows this because Mama used to complain about her. She wasn't sleeping right. She didn't want Mama to hold her. She didn't talk for a while. “I don't understand,” she said. “Diarmuid was talking so early because he was so advanced and she just looks at us when we try to get her to say something.”

“Don't blame me,” Papa said. “Perhaps it's because you spend too much time with our son and not enough with her.”

“Or with you,” Mama said. “That's what you're really trying to say.”

And they started arguing and Diarmuid was pretty sure he knew what the problem was – too many people talking, and no one really listening. But that's why he was the big brother. 

“It's okay,” he told her. “We all love you and we'll wait for you.”

Diarmuid's first word was “Papa,” which Mama never quite got over, though she was pleased when Waver's turned out to be “Mama.”

He never tells her that really, Waver had said “Didi” a week before that.

She catches up quickly, though, and pretty soon he's sure Papa kind of regrets being concerned about her talking.“Why does she keep telling me no!” Papa says one day. “I swear she does it just because she can.”

“You weren't like that, were you, Diarmuid?” Mama coos. “Never difficult and always making it easy for us.”

That night, as Waver gets ready to toddle off to bed, Diarmuid leans down, smiles at her, and tells her, “You're a good girl.”

 

### Six (11)

“Stop crying, Diarmuid,” Mama snaps. “I swear you'd think she was going off to war instead of her first day of school.”

“But Mama,” he starts to say.

“Listen to your mother,” Papa says. “Everyone has to go to school. Otherwise, they'd end up idiots. Even then, most of them still stay that way.”

“I'm not so sure--”

“No, he's right,” Mama says. “Even though it broke my heart to take you on your first day, your little eyes welling with tears and your hands trembling, begging me not to let go of you...”

Diarmuid doesn't remember that, although he does remember being very excited about making new friends and learning new things so he could help out Papa with his work. He loves his Papa dearly, but he's still not quite sure why Papa doesn't feel the same way.

But looking at Papa's face as Mama keeps talking about his first day, he's starting to put it all together.

“I'm going to be late,” a quiet voice says, and Diarmuid looks down to see his little sister tugging at sleeve.

She's the most adorable thing he's ever seen, in her little hat and coat, and he thinks he understands why his mother didn't want to let him go. No one there will know how to make her laugh when she cries, how to get her to fall asleep, how to protect her from everything that wants to hurt her.  Maybe he could convince Mama and Papa to teach her at home.

But he's a good boy, a smart boy just like Mama tells him and he doesn't want any more fighting, so he says, “Well, we don't want you to be late.”

“I'm sure Kayneth will get her there on time,” Mama says. “I've got a meeting with the department that I needed to leave for ten minutes ago.”

“I can't take her,” Papa protests. “My latest assistant is an absolute disaster and I can't leave the class in his hands. Who knows what sort of drivel he'll talk about if I'm not there?”

“They'll survive for a few minutes without you.”

“I'm positive your department can make do as well.”

“I'll take her,” Diarmuid pipes up. “I can do it on my own.”

Both Papa and Mama look hopeful, if slightly dubious at his claim. “Sweetie, are you sure?” Mama asks. “You won't get lost?”

“No,” he says firmly. “I won't.”

He holds Waver's hand all the way there, only letting go when Miss Raikou carefully pries his sister away from him.

“Don't worry,” she calls out cheerfully. “If you run now, you might not miss all of your morning classes.”

He knows he'll get into trouble for leaving school early, but the look on Waver's face when she sees her brother waiting to pick her up is worth any inconvenience he might suffer.

 

### Ten (15)

_Diarmuid just wants to do the right thing, to be a good knight, to have a master that he can serve to the best of his ability. He failed the first time. He won't fail again._

_He knows he's not the one his master wanted, but he'll show him that he can help him. He'll show him that his summoning isn't something to be regretted._

_He first meets the man's “treacherous little rat of a student who stole what rightly belonged to me” in the middle of the first battle and he's not impressed. The boy cowers while his servant booms his name out. The child is clearly no master. But a voice inside him says your master is no master either, forcing you to cheaply attack a worthy opponent. He is thankful when the boy's master dispels the situation, even if his own master is not._

_It's an uphill battle. His master is contemptuous and does not fully value his service. And his master's wife is far too enamored of him. The curse holds true even now, he thinks, and so he is cautious around both, deferential at all times and soon he thinks his master trusts him, calls him to action._

_And then it goes wrong and his master's wife is the one commanding him and he'll serve her too, but his master is broken and there is the start of something dark in his heart, the same voice that whispers you failed him, why should he value your loyalty?_

_Diarmuid meets the boy again when they are fighting Caster and his monster. He takes little note of him except to see that for a child so timid and weak, like his master says, he's the one on the battlefield. Surely, your master would be there, he says to himself, were he not so damaged. But he knows that's not the truth._

_Everything is worse from there. There is little honor left in the fight and soon his mistress is missing. There is desperation in him now, he cannot fail his master again. He thinks at first to wait, to let him handle it._

_But he does not (not this time, he thinks and wonders where that thought came from). He goes to the boy, to Waver, and asks him to help him find his mistress. Please, he begs, let me save them. And Waver, the untrustworthy student, agrees. Yes, he says. I'll help you._

_He does not ask for anything. Waver talks to him, too, and apologizes. I'm sorry, he says. This wasn't what I wanted. I just wanted him to listen to me, to realize that I had value. I wanted everyone to see that what I was saying meant something._

_Diarmuid keeps these words close, as he has kept so many others. If the boy committed treason, it was for understandable reasons and though he is loathe to criticize his master, he can see the blind spots in his thinking._

_But you cannot see your own blind spot, and Diarmuid does not see the betrayal coming. His master orders his death at his own hands, and there is a terrible anger in him, a rage that turns him into a rabid dog, foaming at the mouth and demanding vengeance. A curse starts to spew from his lips._

_He forgets the boy is there too, until he sees him and the boy's eyes, filled with sadness and horror. Waver is mouthing words. It's not right. I'm sorry. You don't deserve this._

_And for a second, the rage subsides and one thought rings through him crystal clear: next time, I wish to serve you. To protect you. It imprints itself upon him even as the wave of his anger drowns him again in darkness and he goes under cursing his former master._

_And the voice in the darkness says, well, that might be interesting. Diarmuid._

_Diarmuid._

_Brother!_

He wakes up with a start. There is a pounding in his head, and when he puts his hand to his forehead, he can feel a cold, wet cloth on top of it. He's lying in his bed with the sun coming through the window. There's a basin of water on the nightstand.

His sister is sitting next to his bed, her eyes red-rimmed. “Are you all right, brother?”

“Waver,” he says weakly.

“You've been really sick. I've been so worried,” she says, and bursts into tears, throwing her small arms around him.

“You're here?”

“Of course I am,” she says, sniffling. “Where else would I be?”

“Right.” The dream is fading away even as he tries to hold onto it, but he remembers the feeling he had. The anger, the rage. “Where's Father? Or Mother?” 

She looks away. “They couldn't be here right now,” she eventually says. Waver's never been a very good liar and he wonders just how many arguments she's heard while he's been out of it.

He feels the bitterness in his heart, a burning on the tip of his tongue, and for a moment, he thinks to say something truly horrible. But his sister's nervous shifting in her chair stops him. He can't do that to her, let her see any more of his hatred.

Any more? Diarmuid shakes his head. “I understand. I'm sorry I worried you.”

“Just don't do it again,” Waver says and takes the cloth off his forehead, dipping it in the basin. “Now you need to rest and get better.”

Yes, he thinks. I need to get back to being strong so I can protect you. I made you a promise.

If that's all he remembers, it's enough.

 

### Sixteen (21)

He never thought he could fail to protect her like this.

Where did his system go wrong? Was it in not making sure he walked her home every day?

“Brother, you don't need to watch me walk in the door. I can make it on my own.”

Was it in going off to university, even though he made sure to pick the closest one?

“Diarmuid, you could go somewhere farther away. Maybe in another country?”

“Kayneth, really. If you want to live at home, Mama will totally understand and support you.”

Was it Grainne's fault? Probably.

“Why won't you pay attention to me? Don't you love me?”

“Not really.”

No, it was everything he did. He swore to always look after her and never leave her side. But he wasn't there when he was needed most. His heart fills with sorrow.

“How could this happen?” he wails. “To think that giant could just come in and sweep her off her feet. Literally!”

The lion nods. It reaches into the picnic basket next to it and pulls out another meat bun.

“And now she won't hear anything bad said about him! I tell her that he's a some sort of dumb military otaku who will never give her the attention she deserves and she just tells me I'm being unfair! He probably set up the whole thing just to be able to play the hero!”

Another meat bun goes into its cavernous maw. A family walking by stares at it, then at Diarmuid. All of them blush.

“I know, I know. I have to let her live her own life. And I'm sure he doesn't want to hurt her. She tells me he's a nice guy.” And he also seems strangely familiar, but Diarmuid tries not to think too hard any time he's reminded of his dreams. “But what if he hurts her on accident? She's so little and he's so big!”

The lion coughs.

“I didn't mean it that way. Just... I want her to be safe and happy. What if he breaks her heart? I can't save her from that.”

The basket now empty, the lion stands up. It pads over to Diarmuid and pats him clumsily on his shoulder with its oversized felt paw.

“Thank you,” he says. “You're a very good listener.”

 

### Eighteen (23)

In hindsight, Diarmuid thinks, he should have agreed with Father.

“Why on Earth would you want to go to something like that?” Father says, setting aside his newspaper on the table. “I can't even imagine what sort of trash they sell there.”

“It's not trash, Papa,” Waver says primly. “It's merchandise related to popular visual narratives that depict commonplace tropes, occasionally set in fantastical or futuristic settings, but often in an academic environment."

Father blinks. “What?”

“Anime,” Diarmuid translates. “It's fairly popular in certain circles.” He gives Waver a look. “And I'm pretty sure I know exactly why she wants to go there.”

“I don't know what to get Iskander for his birthday,” she says. “But I know that the creator of one of his favorite series is going to be there and if I can get something related to it...”

Diarmuid and Father have disagreed on a fair number of points over the years, but the one thing they can unite on without question is a deep mistrust of Waver's boyfriend. “See, this is why he's a bad influence,” Father says. “He's just using you to get things.”

She rolls her eyes. “Papa, he has his own mansion and servants. He buys me things.”

“That's actually true,” Diarmuid admits. Much to his dismay, Iskander is meticulous about remembering every important date in Waver's life and his gift-giving skills have massively improved since that almost disastrous Saber figure day.  

“Well, I think it's romantic,” Mother says. “I remember my first gifts.”

Father's already scowling and Diarmuid's bracing himself for the inevitable gushing. If he has to, he'll discreetly set something on fire to distract them. It wouldn't be the first time. 

“Kayneth bought me a necklace, then took me to the Hyatt for dinner. It was really quite lovely,” she says.

“And you gave me a pair of compression gloves because I said my hands hurt and you said I needed to take better care of them,” Papa replies. The smile on his face is wistful. “I still have them.”

“You do?”

“Of course.” They exchange fond glances which send Diarmuid aback. When was the last time he saw that? Ever? He eyes them suspiciously. 

Waver, being the clever girl that she is, seizes the moment. “So can I go?”

“Not by yourself,” Father says. “Who knows what sort of degenerates prey upon girls there?”

"Mama?"

"You heard Papa," Mother says. "But if you can find someone we trust to take you, I guess it would be all right."

Diarmuid gets a sinking feeling as Waver's eyes meet his. There's a calculation in them that seems at odds with his innocent baby sister. 

“Waver,” he says weakly.

“Brother?” He falters.

"I don't think." Diarmuid swallows. "I mean, it's just--"

“Please?” Her eyes are wide, pleading. "For me?"

He slumps in his chair in defeat. “Fine.”

Surely, it won't be that bad. He'll be with his beloved little sister and he'll be helping her out... by buying a gift for her boyfriend. That man.

Just do it for Waver, he thinks. You can survive this.

“I don't think I'm going to make it,” he says, four days later, having managed to make his way outside to breathe a little. “I didn't think it would be this crowded!”

The lion is still patting his back. He's breathless from when it saved him by barreling through a crowd of teenage girls that were surrounding him, throwing him on its back, and making a dramatic leap over several tables and sellers to land outside.

“But thank you for saving me,” he says, bowing his head. “Now we just need to find my sister.” His blood runs cold in terror. He swore to protect her and--

He can't panic now. Waver is counting on him to find her, to rescue her from wherever she ended up after they got separated in the crowd.

The lion holds up a paw.

“I can't wait,” he says desperately. “She might be in terrible danger!”

It holds up its other paw.

“I don't care.” He straightens his collar, fixes his jacket. Nothing will stop him now, not man, not woman, not oversized mascot that is clearly capable of tackling him to the floor and looks like it's going to do so. “I'm going to--”

“Brother?”

“Waver!” Diarmuid just has to turn around, take her hand and--

“Oh,” he says. “You're here too.”

The man awkwardly scratches his head. “Yeah, we ran into each other.”

Waver blushes. “It was supposed to be a surprise, Iskander. Now you're going to know what I'm getting you.”

“You—you don't have to get me anything,” he stammers. “You just being with me is enough.”

She smiles. Diarmuid's annoyed. “Well, she came here for you,” he says. “So be appreciative of that.”

“I am,” he says and it's hard to stay mad when Iskander's eyes are this filled with love and devotion.

“Good,” Diarmuid says. “If we're done, let's go.”

“But we didn't to get to see Saber, Brother,” Waver says. “She was supposed to be here and no one's seen her.”

(Off in the distance a voice wails “My beloved Saber, where are you?”

“Now now, young master, you are being most unseemly.”

“Shut up, Kirei. And why did you bring him here, Enkidu?”

“You know someone has to make sure you don't get into trouble. We don't want any more restraining orders.” A knowing laugh. “Of course, I'll let you restrain me anytime.”

“But Saber!”)

“I thought Saber wasn't real,” Diarmuid says.

“Well, the character isn't, but the actress playing her in the series was supposed to be here. They modeled Saber directly from her.” Waver looks a little unhappy. “She's supposed to be really pretty.”

“It's all right,” Iskander reassures. “No one can compare to you.”

“Iskander.” More blushing.

Diarmuid either wants to throw up or throw something. He settles for letting the lion hold his hand as they leave the center.

“At least it can't get any worse than this.”

 

### Twenty-two (27)

“You look beautiful,” he says to her and means it. Somewhere out in the church, Father is probably crying and blowing into a handkerchief. He's been doing nothing but that ever since Iskander asked for Waver's hand in marriage.

_“I told him he didn't have to,” Waver said. “It's an outmoded tradition and insultingly patriarchal. We're trying to move forward, not be stuck in the past. But he said Papa would appreciate it.” She scowls, resembling their dad. “I'm beginning to be a little worried by how well they're getting along now.”_

_“You know you don't have to marry him,” Diarmuid replied._

_She laughed. “I know. But I want to.”_

_And he left it at that._

“Thank you,” she says. “I feel like a giant poofball in this.”

“Or a queen?” His little sister looks positively regal in her dress. 

“I don't know why Mama insisted on the tiara.”

“I think she's more into the wedding than you.” Upon the announcement, Mother immediately threw herself into a frenzy of planning, creating countless wedding books, calling multiple vendors and venues, and in short, driving everyone but Father nuts.

They exchange knowing glances. “Well, at least they're happy,” Waver says. “I think Papa even cried on your shoulder once.”

He did. He also told Diarmuid he was proud of him and that he loved him. Diarmuid knew that after Father sobered up, he'd probably forget most of it, but that was okay. Diarmuid would keep it close to his heart, a memory he'd guard as fierce as he guarded everything that mattered to him.

"Everyone's very emotional,” he tells her. "Things will calm down."

Waver smiles at him, her face radiant in the sunlight streaming through the window. Before he can think, she crashes into him like a white satin wrecking ball and hugs him tightly. He hugs her back, trying not to wrinkle her dress. He doesn't want to ruin anything for her. 

She holds on to him for some time. He thinks she might be crying a little, sniffling into his coat, but when she pulls back from the hug, her eyes are only slightly red. 

"I'm going to miss you," he blurts out, and then mentally kicks himself. Don't do that, he thinks. Don't make her unhappy.

But Waver only smiles, a tiny wistful one this time. She takes Diarmuid's hand into her own small gloved one. “It'll be all right,” she says. “I'm happy. I'll be happy. And we'll still see each other. It's not the end.”

“I know it's not,” he says, surprised by her sudden solemnity. “I just--”

“And you deserve to be happy too. You've been through so much.”

He laughs, uncomfortable. “Well, Father's gotten better,” he says. “And Mother's gotten a lot less clingy since we've grown up."

“That's not what I mean.” Waver takes off her gloves and traces an invisible symbol on her hand. 

A corresponding vision of red flashes before his eyes. He shakes his head.

"Waver--"

“You've fulfilled your vow.”

There's too much overwhelming him right now -- grief and pain and an anger that leaves because he did it right this time and--

He can't speak and clutches at her hand desperately. She lets him.

They're silent for quite some time.

Eventually he removes his hand and she takes a tissue from the table to wipe the tears he hasn't noticed falling down his face. “Just be happy,” she breathes. “That's my final command to you.”

“I accept.”

Diarmuid bends down to kiss her hand gently where she traced the symbol, then straightens back up.  He lets himself take one last look at her jubilant smile before he leaves her to her wedding, to her marriage, to the man she's found once again to protect her. His job may be over now, but he knows it's not the end.

He walks outside to collect himself, take a deep breath. The guests are still arriving, filling up the church. It's a little chilly out, but there's no clouds in the sky. It's going to be a lovely day.

“Are you going to be all right?” a soft voice asks.

A young blonde woman dressed in a dark suit walks up to him. She's smiling hesitantly. 

“I'm sorry,” he says. “Do I know you?”

“Yes,” she replies. “I think you'll find you do.”

He closes his eyes once as a dream, long forgotten, returns to him. He opens them again. It seems like it's a good time to take his sister's advice.

“Not wearing the lion suit today?”

Her smile broadens. “Only for special occasions. Like when an old friend needs someone to lean on.”

Artoria offers him her arm. Diarmuid takes it.

And they walk into the church towards whatever the future might hold.


End file.
